In order to electrically activate an impurity implanted into a single crystal silicon carbide (SiC) substrate, an activation annealing processing process is performed at a high temperature. However, when the impurity in the silicon carbide (SiC) substrate is subjected to activation annealing, the surface roughness of the substrate disadvantageously occurs.
As methods of solving this problem, a method of adding a silane (SiH4) gas to perform annealing (see non-patent document 1), a method of applying a carbon coating to a substrate to be processed to perform annealing (see patent document 1) and a method of performing annealing under an atmosphere in which the partial pressure of the remaining water is reduced in a high vacuum region (see patent document 2) are known. Patent document 3 discloses that an epitaxial layer is formed on a substrate, an ion implantation layer is formed on a surface of the epitaxial layer, high temperature annealing for the activation of an impurity is performed and thereafter the surface (the surface of the ion implantation layer) of the single crystal silicon carbide (SiC) substrate is subjected to plasma etching using plasma.    [Patent document 1] Japanese Patent Application Laid-open No. 2005-39257    [Patent document 2] International Publication No. 08/136,126 Pamphlet    [Patent document 3] Japanese Patent Application Laid-open No. 2001-35838    [Non-patent document 1] M. A. Capano, S. Ryu, J. A. Cooper, J R., M. R. Melloch, K. Rottner, S. Karlsson, N. Nordell, A. Powell. and D. E. Walker: J. Electron. Mater, P214-218, Vol. 28, No. 3. (1999)